The Best Time to Take Your Thyroid Medication

Early Morning Is Still the Standard, but the Evening May Be an Alternative

If you are on thyroid hormone replacement medication, guidelines recommend that you take your thyroid pill first thing in the morning with water, on an empty stomach, and wait at least an hour before eating or drinking coffee. 

Moreover, you should also wait for at least three to four hours before taking any other medications that interfere with its absorption, like iron tablets or calcium carbonate.

However, two research studies—one published in the Journal of Clinical Endocrinology and Metabolism and a follow-up larger randomized trial reported in the Archives of Internal Medicine—found that taking the same dose of levothyroxine (for example, Synthroid or Levoxyl) at bedtime, as compared to first thing in the morning, may actually be better.

when to take levothyroxine thyroid medication
​Illustration by Emily Roberts, Verywell

Research Suggests Nighttime May Be Better

The study reported in the Journal of Clinical Endocrinology and Metabolism looked at the impact on thyroid hormone blood tests by changing the time levothyroxine was taken from early morning to bedtime. The study also evaluated the impact of this dose timing change on the circadian rhythm of thyroid-stimulating hormone (TSH).

The study, while small, was fairly conclusive in its findings, which the researchers said were “striking” and which have “important consequences for the millions of patients who take l-thyroxine daily.”

Study Results

In all the patients, TSH decreased and free thyroxine (T4) levels rose by changing thyroxine ingestion from early morning to bedtime. Triiodothyronine (T3) levels rose in all but one subject. 

Interestingly, TSH decreased irrespective of the starting TSH levels, suggesting better absorption of the thyroid medication when taken in the evening.

Lastly, researchers found that the circadian TSH rhythm – the typical daily fluctuations of TSH that occur during a 24-hour period – did not vary.

Study Discussion

The researchers suggested several explanations for the results:

  • Even when waiting for at least 30 minutes to eat, breakfast may be interfering with the intestinal absorption of levothyroxine. 
  • “Bowel motility is slower at night,” which means that it takes longer for the levothyroxine tablet to transit through the intestinal system, resulting in longer exposure to the intestinal wall, and therefore, better absorption and uptake of the medication.
  • The conversion process of T4 to T3 may be more effective in the evening.

The researchers from this study suggested that given the results of this study, a large double-blinded randomized study was needed to confirm their results – and this was the study reported in the Archives of Internal Medicine.

Second Suggests Nighttime May Be Better

In this study, 90 patients completed the trial, which involved a six month period of taking one capsule in the morning and one capsule at bedtime (with one capsule active levothyroxine, the other a placebo, and a switch at the three-month point).

The researchers evaluated thyroid hormone levels, as well as creatinine levels, lipid levels, body mass index, heart rate, and quality of life parameters.

Study Results

The researchers found that the patients taking nighttime levothyroxine had a drop in TSH of 1.25 mU/L, a significant change. The free thyroxine (free T4) level went up by 0.07 ng/dL, and total triiodothyronine (total T3) went up by 6.5 ng/dL. There were no significant changes in the other factors measured.

Study Discussion

The researchers concluded that, given the improvement in thyroid hormone levels, physicians should consider prescribing levothyroxine to be taken at bedtime.

Implications for You or Loved One With Hypothyroidism

Taking medication at bedtime instead of in the morning could offer some upsides:

  • First, it’s easier, as you don’t have to worry about when to eat breakfast.
  • Second, it’s easier to avoid medications, supplements, and foods, like calcium, iron, and high-fiber foods that can interfere with thyroid medication absorption.
  • Third, coffee drinkers don't have to wait until an hour after their medication to enjoy their first cup.
  • Fourth, it might offer some improvement in symptoms if you are not getting optimal absorption by taking your thyroid medication during the day.
How to Properly Take Your Thyroid Medication

These studies confirm what many patients anecdotally have been reporting for years – they feel better if they take their thyroid medication in the evening, rather than the morning.

In the end, though, it's important to talk with your doctor about changing the time to take your generic levothyroxine or brand name levothyroxine (for example, Synthroid). If you and your doctor decide to give it a go and take your thyroid medication in the evening, be sure to have your thyroid levels evaluated (six to eight weeks is a reasonable timeframe) after you’ve made the switch.

The blood test results, along with any improvements or worsening of symptoms, will help you and your doctor determine if you need to adjust the dosage or revert back to taking your medication in the early morning

Important Point to Keep in Mind: Studies Only Evaluated Levothyroxine

These studies were conducted with levothyroxine, a synthetic form of the long-acting T4/thyroxine thyroid hormone. This form of the hormone must first be converted in the body to the active form (T3), and this can take days.

Thyroid drugs that contain T3 – such as Cytomel, and the natural desiccated thyroid drugs like Nature-throid and Armour Thyroid – are used directly by the body within hours. These drugs were not evaluated in the study, and it's not known if medications containing T3, or natural desiccated thyroid drugs would be better absorbed at night.

Anecdotally, some thyroid patients have reported improvement in symptoms when taking some or all of their T3-based thyroid hormone replacement medications in the evening. But some thyroid patients also find that if they take a medication with T3 later in the day or in the evening, the slight stimulatory effect of the T3 medication can make it difficult to sleep.

So keep in mind that while it's possible that if similar studies were conducted with T3 drugs, the results would be similar, but there is a chance that it would impact sleep quality in some patients. You should only make such a change after discussing it with your doctor.

Some doctors have suggested that patients who take T3 medications use a time-released or sustained release formulation of T3, or split their doses and take their medication several times throughout the day. This approach seems to minimize sleep interference; however, again, be sure to only change the dosing under the guidance of your doctor. 

If you do make a change to how you take your T3 thyroid medication, you'll want to have a reevaluation of blood levels and symptoms after several weeks, to determine if you need to adjust the dosage or timing of your medication.

A Word From Verywell

While standard guidelines suggest taking your thyroid hormone treatment first thing in the morning on an empty stomach (due to the risk of food interfering with absorption), taking your thyroid medication in the evening may be sensible in some cases.

This may be especially true for people who find it difficult to wait an hour before eating in the morning and/or who are taking other medications in the morning. 

In the end, the key to taking your thyroid hormone replacement medication is consistency, taking your thyroid pill around the same time each day, and in the same way.

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View Article Sources
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